<!DOCTYPE html>
<html lang="en">
  <head>
      <meta charset="UTF-8">
      <title>在head标签中，使用style标签来定义需要的css样式</title>
      <style type="text/css">
        div {
          width: 300px;
          height: 100px;
          background-color: beige;
        }
        span {
          border: 1px solid red;
        }
      </style>
  </head>

  <body>
    <div>hello, 北京</div>
    <br/>
    <div>hello, 上海</div>
    <br/>
    <span>hello, span</span>
  </body>
</html>